Pipeline scraper-locator transmitter



J. E. BELL PIPELINE SCRAPER-'LOCATOR TRANSMITTER Filed March 5, 195e' 3Sheets-Sheet 1 ATTORNEY Jan. 21, 1958 J. E. BELL PIPELINESCRAPER--LOCATOR TRANSMITTER 3 Sheets-Sheet 2 Filed March 5. 1955ATTORNEY .mi mw m 5 w. E.

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Jan. 2E, 1958 J'. E. BELL PIPELINE scRAPER-LocAToR TRANSMITTER 3Sheets-She'ei: 3

Filed March 5. 1956 ATTORNEY United States Patent C PIPELINEscRAPER-Locaron 'rRANsr/rrrrnn James E. Bell, Whiting, Ind., assignor toStandard Oil Company, Chicago, Ill., a corporation of IndianaApplication March 5, 1956, Serial No. 569,579

6 Claims. (Cl. 340-282) This invention relates to apparatus fordetermining the location of cleaning tools in pipelines and refers moreparticularly to signaling devices for locating or tracing the course ofcleaning apparatus in pipelines. Pipelines frequently become obstructedwith sediment, deposited parains, and the like and must be kept clean inorder to restore normal unobstructed flow of the line. A device commonlyemployed for such cleaning is a uidimpelled scraper which is forcedthrough pipelines by the flowing fluid. The operation of such pipelinecleaners is attended by the disadvantage that they occasionallyencounter, and are stopped by, obstructions which trap the cleaner. Theyare then diiiicult to locate, particularly inasmuch as they are oftencarried over considerable distances within a line and their rate oftravel can only be approximated.

Heretofore, various systems have been proposed for locating the pipescraper and such systems have included sonic emitters, radar echoing,radioactive sources, and others. However, each of these systems has beenlimited in its application to pipeline operations and, therefore, nonehas been generally suitable and foolproof in use.

It is, therefore, a primary object of my invention to provide signalapparatus adapted to be carried by a pipeline scraper whereby theposition of the scraper can be located at any time during its travelthrough a pipeline and at any point within a pipeline. It is a furtherobject of the invention to provide an apparatus which is capable ofemitting a signal of such strength and for such duration as to permit apipeline walker to locate a stuck cleaner. Still another object of theinvention is to provide a transmitter for use on pipeline Scrapers whichis rugged, relatively simple in construction, and foolproof inoperation. It is also an object of my invention to provide an apparatuswhich will give a positive indication of its location when a pipeline issurveyed by an electromagnetic-sensitive receiver. Still another objectis to provide an apparatus which will enable one without special skillsto search out and locate the trapped pipeline cleaner of theuid-impelled type. These and other objects of the invention will becomeapparent as the description of the apparatus is hereinafter given.

I have found that the aforementioned objects can be attained byproviding a low frequency electromagnetic wave generator which will giverise to an induced eld external of the pipe and will produce a readilyidentifiable signal over a rather wide area at the surface of theground. Briefly stated, the present invention comprises an improvedsource of electromagnetic waves having an electronic driving circuitwhich permits the use of a suitable receiving apparatus adapted toreceive, amplify, and convert the electromagnetic impulse to an audible,visual or recorded signal.

Further details and advantages of my invention Will be described inconjunction with a preferred embodiment thereof illustrated in thedrawings wherein:

Figure 1 is a simplified elevational view of a pipeline scraper, partlyin section, embodying my transmitter;

2,820,959 Patented Jan. 21, 1958 rice Figures 2 and 3 are schematicdiagrams of the transmitter;

Figure 4 is a section taken along the line 4 4 in Figure l showing theconstruction of the electromagnet utilized in the transmitter;

Figure 5 is a fragmentary enlarged view, with some parts removed, takenalong the line 5 5 in Figure 1;

Figure 6 is a block diagram of the receiver apparatus as used to locatethe pipe within which the scraper is traveling; and

Figure 7 is a block diagram of the receiver apparatus suitable for usein locating the transmitter of Figures 2 and 3.

Briefly, the complete scraper locator comprises a transmitter and areceiver, the transmitter being so designed that it can be carried by apipe scraper and placed within a pipeline, whereas the receiver can becarried above the ground. The transmitter is located within its ownhousing to which different sized rubber cups can be adapted and it canbe used in several ways. It can be used as batch scraper itself and itsmovement can be followed either by spot checking as it passes under roadbeds or it :can be followed by walking along and keeping its signalwithin range which is of the order of about 2O feet. Another procedureis to place it in tandem with another scraper and follow it asdescribed. However, it finds its greatest utility in locating a trappedscraper which has become stuck in the line by allowing the transmitterunit to travel through the pipeline until it reaches the stuck scraper.

A generally acceptable receiver for use in conjunction with mytransmitter is described in Brenholdt 2,601,248. However, it is withrespect to the transmitter itself that my invention is particularlydirected and the construction and operation of the receiver will bedescribed only in general terms.

Referring to the drawings, the transmitter 1li comprises abattery-powered drive unit 11, 21 and 22, driving a laminated-coreelectromagnet 12. This assembly is mounted with a stainless steelhousing 13 provided with end plates 14 which can be secured withinretaining rings 15 and used in different sized pipelines 16 by providingappropriately sized rubber cups 17. The transmitter 10 includes abattery 18 which is preferably a large 9-volt supply constructed ofmercury cells. The transistor driving unit is a three-stage circuitconsisting of an 18-C. P. S. multivibrator 11, a grounded collectoramplier 21 and a grounded collector power output stage 22. Transistorsare used because of their low power consumption and small spacerequirements.

The circuit of Figure 2 employs a low-frequency multivibrator as anoscillator 11 operating at approximately 18 cycles per second forproducing the driving power. A large amount of positive feedback isprovided to produce oscillation. A small amount of negative feedback isused to present the correct A. C. input impedance for the desiredoscillation frequency. rlhis provides the temperature compensationnecessary in transistor circuits and allows the use of the correct D. C.bias at the desired A. C. impedance. The signal from the multivibrator11 is coupled into the high-current-gain grounded collector amplifier 21which uses the power transistor circuit 22 as its load. The powercircuit 22 is also a grounded collector configuration. The use of onetransistor 33 as a direct load on the other transistor 32 allowspractically all the current drawn from the battery 18 to be utilized inthe electromagnet 12 which is the load on the power stage 22.

The transistor driving unit 11, 21 and 22, the electromagnet 12, and thebattery 18 are placed within a stainless steel housing 13. Standardrubber cups 17 are mounted at opposite ends of the housing 13 to adaptto any oscillator circuit 11 as shown in Figure 3.

sized ,pipe .from 8 inches .to .24 .inches in diameter. .The housing enddiscs 14 are held within the clamping rings 15 which are mounted on therubber cups 17 by means of plates and bolts 26.

The transmitter coil 12 is a single coil consisting .of windings 27around a 4"large .single Vcore .28 V:of laminated iron, as .shown inFigure 4, .in Vorder `to vobtain 'the .largest possible magnetic fieldaround the coil i12 vfor a practical power 'consumption from the battery18. Standard .high silicon audio transformer iron (0.014 inch thick)-cut to different widths but all of the .same length comprise the core28 Vof vthe transmitter coil ,12. The laminations reduce eddy currentsVand, therefore, lower the ycore loss. The Ystrips are then stacked so:as to approximate'a circular vform for the cross-section ofthe bundleof strips, lthe strips being well insulated from each other and theentire bundle of strips being insulated from the windings with tape (notshown) to prevent -shorting of Ithe Vwire coil 27 to the core 28. Thelend -plates 29 are held in place by tie rods 30.

Referring to Figure 5, the switch 31is mounted on the base 29 forconnection as shown in Figure 3. Transistors 23, 24 and 32 together withpower transistor 33 are supported by the plate 29 and connected in andto the A plurality of spacers 34 space the electromagnet 12 within thehousing 13 from the end plate 14.

The transmitter 10 should be put into operation just before it isinserted into the pipeline 16. 'This is done by inserting an appropriatetool in the slot on control shaft 35 on the switch 31 located within thepipe nipple 36 on one end 14 of the housing 13 kas shown in Figures land 5. The slotted shaft 35 is turned clockwise about 1./6 `revolutionuntil the switch 31 vis turned on, switch 31 being turned oi byreversing the turning movement.

The bore 37 in the plate 25 and in the rubber cup 17 permits accesstothe cap 38 and to the switch control shaft 35 through the nipple 36which is welded to the end plate 14, the shaft 35 being sealed withrespect to the end .plate 14 by O-ring gasket 39. The pipe cap 38 mustbe secured on the nipple 36 at all times to -protect the switch actuator35 when the transmitter unit 10 is in the pipeline 16.

The receiver is built toserve a dual purpose ofa pipeline locater(Figure 6) or as a scraper-transmitter locator (Figure 7). It detectsand audbly indicates the presence of any iuctuating magnetic field `witha frequency in the range of about 12 C. P. S. and about .25 C. P.. S.Consequently, a certain amount of background noise may be heard in thereceiver when it is carried or moved since the receiver core may becutting the earths eld or other stray magnetic fields at a frequency inthe above range of sensitivity.

Pipelines using cathodic protection have full-Wave rectied 60 C. P. S.voltage applied to them so that it appears as though there were 120 C.P. S. current in the pipeline. These currents create a magnetic eldwhich can be detected by the receiver.. Similarly, a pipeline withoutcathodic protection normally has a 60 C. P. .S. iield around it due tocurrents caused by pickup from power lines, etc. Both of thesefrequencies can be detected by proper tuning of the receiver.

The receiver circuit shown in block form in Figures 6 Yand 7 contains apickup coil 50 which is tuned to the desired frequency, i. e. 18, 60 or120 cycles. A three-position switch (not shown) on amplifier 52 allowstuning to three separate frequencies of 120 C. P. S. for pipes withcathodic protection, 60 C. P. S. for pipes without cathodic protection,and 18 C. l. S. for detecting the transmitter 10.V The signal is fedfrom the pickup coil into a ythree-stage tunedamplitier 51, 52,53, thetuning of which is accomplished in the second stage by negative feedbackthrough a twin T filter of all frequencies except those near the one towhich the pickup lcoil 50 is tuned,

VReferring to the 4blockdiagrams of the receiver .apf paratusillustrated in Figures 6 and 7, the pickup coil 50 intercepts anoscillating magnetic eld. A major portion of the frequenciesincidentally produced by movement in the earths field of the receiverapparatus, which can be portable and is ordinarily housed in a carryingcase, are eliminated by using va1-tuned amplifier 52 and by the -biason-the modulator stage 55. The Yfilter 57 eliminates 60 cycle pickup frompower line, railway tracks, etc., whenthe Areceiverfis being used asascraper l-locator. The resultant signal from ythe pickupcoil 50 Eorftromthe lilter 57 is Vdirected .to an `amplifier circuit .51, -the ampliedsignal being thereafter directed to an amplifier circuit 52 tuned totheldes'ired frequenoyand thence to an addtional amplifier 53. Thesignal from 53 serves to gate a 1500 C. P. S. signal produced by theoscillator 54 whereby the 1500 C. P. S. signal is permitted to passthrough the modulator and` output circuit-55 -only Lat -the VAselectedC. P. S. intervals. Thisaudible signal is received -by the crystalYphones .56.

To operate the receiver in locating aipipeline, the coil 50 yis tuned tothe vdesired frequency, i. e. 60 kor 120 C. `P. S., and then theoperator Vwalks back and forth transverse to the expected direction ofthe 'buried pipeline 16 and a maximum signal is detected when'thereceiver crosses the pipe location.

To locate -the transmitter, the "receiver is Atuned to the transmitterfrequency of l1S C. P. S. and if the transmitter 10 is withinapproximately 20 feet of the receiver a very steady tone `is heard in'the earphones 56 associated with the receiver.

The 'detected signal is of 'such a low frequencyf'that it is.practically inaudible. Therefore, this signal is used only as a gateYto allow the passage of a V1500 cycle signal from oscillator '54 throughthe last stage 55. YThe higher frequency 'is obtained from aneon bulbrelaxation .oscillator 54 and this 1500 cycle oscillation is impressedupon the output stage 53, but the tube remains in a cut-ott conditiondue to the large negative bias until a signal is coupled to it from theamplier .55. The tube is 'then driven out of cut-ott and this allows.the modulated .1500 cycle signal to be coupled to the high vimpedance'crystal head phones 56.

Although I have described my inventionin terms 'of a preferredembodiment thereof, which is set forth .in some detail,l it should beunderstood that this is by -way of `illustration only and .that theinvention is notnecessarily limited thereto. Alternative embodiments andoperating techniques will become apparent to those vskilled in the artin view of my disclosure and, accordingly, it is contemplated thatmodifications can be made in the apparatus without .departing from thespirit of the described invention.

What I claim is:

f1. A signal transmitter for use in locating .a pipeline scraper whichcomprises la closedlhousing, a pair of propulsive cupssupporting-eachend of said housing, an electromagnetic wave transmittermounted within .said

housing with its axis co-axial with the raxis lof the pipe,

an electronic power drive for'said transmitter withinsaid housing,a'battery means for energizing said electronic power drive, switch meanscontrolling said drive mounted adjacent one end of said housing, andmeans operable through one lof saidpropulsive cups for actuating saidswitch means.

2. A signal transmitter for use Vin indicating the location of apipeline scraper within `a .pipeline which'comprises in combination `anelongated housing, ran electromagnet, an oscillator, an amplifier forthe signal'from'said oscillator, vand a power stage for saidelectromagnet, said oscillator, amplifier, power stage, andelectromagnet being housedrwithin said elongated casing withs'aidelectromagnet being arranged therein with its axis coaxial with the axisofsaid elongated casing, and plates on said casing,

a pair of propulsve cups removably xed to said end plates, and switchcontrol means extending through one of said propulsive cups forcontrolling the said transmitter.

3. An apparatus for transmitting an electromagnetic signal from within apipeline which comprises in combination a pair of propulsive cups, acasing mounted between said cups, an electromagnet within said casing, atransistor driving circuit for said electromagnet disposed within saidcasing, and battery means for energizing said circuit, said drivingcircuit including an oscillator, amplitier, and a power stage, allcontained within said casing, and switch means for controlling saidtransistor driving circuit, said switch means having an actuatingelement extending exterior of said casing.

4. An apparatus for transmitting an electromagnetic signal from within apipeline which comprises in combination a pair of propulsive cups, acasing mounted between said cups, an electromagnet, a transistor drivingcircuit for said electromagnet, said driving circuit including arelaxation type transistor oscillator, amplifier, and a power stage, andbattery means for energizing said circuit, all contained within saidcasing, and switch means having an actuating element extending exteriorof said casing and accessible through one of said propulsive cups.

5. A signal transmitter for use in indicating a location within apipeline which comprises in combination a relaxation type transistoroscillator having transistor circuit components, a transistor circuitamplifier for the signal from said oscillator, an electromagnet, and apower stage for said electromagnet, said oscillator, amplifier, powerstage, and electromagnet being housed within an elongated casing, meanson said casing carrying a pair of propulsive cups, and switch controlmeans extending through one of said propulsive cups for controlling thesaid transmitter.

6. A receiver adapted for use with the transmitter of claim 5 whichincludes a pickup coil tuned to the sine wave frequency of thetransmitted signal, a three-stage tuned amplier, the second stage ofwhich is tuned to the transmitted signal, an oscillator producing asignal of known frequency, the signal from said amplifier serving togate the signal from said oscillator to a modulator and output circuit,and means for receiving an audible signal identifiable with the signalfrom the transmitter.

References Cited in the tile of this patent UNITED STATES PATENTS2,601,249 Brenholdt June 24, 1952

